Methods and systems for provisioning emergency numbers

ABSTRACT

There is provided a method and device for provisioning emergency number information on a user equipment. When a dialed number matches an emergency number from the provisioned emergency number information, the user equipment selects either the circuit switched domain or the packet switched domain and executes a call setup procedure for that domain.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/408,144 filed May 9, 2019, which is a continuation of U.S. Pat. No.10,349,257, issued on Jul. 9, 2019, which claims priority to U.S.Provisional Application No. 62/611,992 filed Dec. 29, 2017 by JanHendrik Lucas Bakker, et al. entitled, “Methods and Systems forProvisioning Emergency Numbers”, all of which are incorporated byreference herein as if reproduced in their entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to methods and systems for provisioningemergency numbers on a wireless device.

BACKGROUND

Telecommunication services are offered via Public Land Mobile Networks(PLMNs) to a user equipment (UE). A user may operate the UE. A PLMN istypically subdivided into an access network, a core network and anInternet Protocol (IP) Multimedia Subsystem (IMS). Services aretypically provided by a user's home network. When the user is using anon-home network, the visited network may have a relation with theuser's home network. Some communications transmitted by the UE arecommunicated all the way back to the home network, via the visitednetwork.

These communications may take different routes, travel through differentnetwork elements based on for example the type of relationship betweenthe home network and the visited network, or based on the technology ofthe networks. For example, a 5^(th) Generation (5G) core network hasdifferent network elements compared to an Enhanced Packet Core (EPC)network.

The IMS may comprise a Proxy Call Session Control Function (P-CSCF). TheEPC may comprise a Mobility Management Entity (MME) or a Packet DataNetwork (PDN) Gateway (GW), and the 5G Core Network (CN) may comprise anAccess and Mobility Management Function (AMF) or User Plane Function(UPF). A CN supports the IMS.

Networks may offer a Circuit Switched (CS) domain, where traditionallyvoice calls and emergency calls are handled, or a Packet Switched (PS)domain, offering PS services including access to the IMS.

The PS domain supports emergency services via the IMS. A UE may supportaccessing one or both of the CS domain and PS domain. A UE able toaccess the PS domain may also support accessing the IMS.

When an emergency call attempt is not detected as such by the UE on thePS domain, the UE may be redirected. Several forms of redirection existand some of them may occur in a sequence. When an undetected emergencycall attempt is redirected, the UE needs to retry the call usingemergency procedures. The redirection and retrying is time consuming andmay cause the user to terminate the call attempt. These problems areonly exacerbated if the user subsequently retries the emergency call.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be better understood with reference to thedrawings, in which:

FIG. 1 is a diagram illustrating various communication paths between formessages from a UE to a Public Safety Access Point.

FIG. 2 is a diagram illustrating a roaming architecture for 3GPP accessfor home routed traffic.

FIG. 3 is a diagram illustrating request and response protocols forobtaining an emergency document.

FIG. 4 is a conceptual diagram of a user equipment in accordance with atleast some embodiments of the present disclosure.

FIG. 5 is a conceptual diagram of a network element in accordance withat least some embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE DRAWINGS

According to at least one embodiment of the present disclosure, there isprovided a method by a User Equipment (UE) for using emergencyinformation, comprising transmitting a request message as part of aNetwork Access Stratum (NAS) procedure; receiving, in response to therequest message, a response message comprising a list of at least oneemergency number; determining that a dialed number matches the at leastone emergency number; when determining that the dialed number matchesthe at least one emergency number, selecting a domain to perform a callsetup procedure, wherein the call setup procedure comprises at least oneof a basic call setup procedure and an emergency call setup procedure;when the selected domain is a Packet Switched (PS) domain, performing anemergency call setup procedure; and when the selected domain is aCircuit Switched (CS) domain, performing a basic call setup procedure.

According to at least another embodiment of the present disclosure,there is provided a User Equipment (UE) comprising: a processor; and acommunications subsystem; wherein the processor and the communicationssubsystem cooperate to: transmit a request message as part of a NetworkAccess Stratum (NAS) procedure; receive, in response to the requestmessage, a response message comprising a list of at least one emergencynumber; determine that a dialed number matches the at least oneemergency number; when determining that the dialed number matches the atleast one emergency number, select a domain to perform a call setupprocedure, wherein the call setup procedure comprises at least one of abasic call setup procedure and an emergency call setup procedure; whenthe selected domain is a Packet Switched (PS) domain, perform anemergency call setup procedure; and when the selected domain is aCircuit Switched (CS) domain, perform a basic call setup procedure.

According to at least another embodiment of the present disclosure,there is provided a non-transitory computer readable medium havingstored thereon executable code for execution by a processor of a UserEquipment (UE), the executable code comprising instructions for:transmitting a request message as part of a Network Access Stratum (NAS)procedure; receiving, in response to the request message, a responsemessage comprising a list of at least one emergency number; determiningthat a dialed number matches the at least one emergency number; whendetermining that the dialed number matches the at least one emergencynumber, selecting a domain to perform a call setup procedure, whereinthe call setup procedure comprises at least one of a basic call setupprocedure and an emergency call setup procedure; when the selecteddomain is a Packet Switched (PS) domain, performing an emergency callsetup procedure; and when the selected domain is a Circuit Switched (CS)domain, performing a basic call setup procedure.

While examples in this disclosure are specific to 5G, Long TermEvolution (LTE), Enhanced Packet System (EPS) and Enhanced UniversalMobile Telephony System (UMTS) Terrestrial Radio Access Network(E-UTRAN) examples, it should be noted that the methods, devices, andsystems described herein are not limited to those systems or radioaccess technology, and could be re-used in other systems or radio accesstechnologies. For example, the methods, devices, and systems describedherein could be used with systems including, but not limited to, ThirdGeneration Partnership Project (3GPP) General Packet Radio Service(GPRS) Enhanced Data Rates for Global Evolution (EDGE) Radio AccessNetwork (GERAN), UTRAN, 2G or 3G Core Networks, 3GPP 5G, 3GPP New Radio.Also, non-3GPP systems are not excluded, such as Institute of Electricaland Electronics Engineers (IEEE) systems or Wireless Local Area Networks(WLANs).

Two sets of emergency services exist: a first set where the UE can beconfigured to detect that a number is an emergency number, andsubsequently execute domain specific emergency call procedures; and asecond set where the network can be configured to detect that a numberis an emergency number. The network (i.e. P-CSCF) may inform the UE thatan emergency number was detected. The UE subsequently performs domainspecific emergency call procedures or basic call procedures.

While the CS domain supports handling of numbers from the second setefficiently, the IMS or PS domain may be configured to redirect the callsetup request. Redirection could lead to attempting the call on the CSdomain as a normal call, attempting the call on the CS domain as anemergency call, or attempting the call via the PS domain using emergencycall procedures. Subsequent to performing emergency call procedures withthe PS domain, the UE may perform emergency call procedures with IMS.Emergency call procedures are also known as emergency procedures. Theterm call is applicable to the CS domain. However, it is also usedinstead of the term session. Sessions are typically established via thePS domain using IMS or Session Initiation Protocol (SIP).

A UE may be in CONNECTED mode, or in IDLE mode. A UE is in CONNECTEDmode when a Network Access Stratum (NAS) signalling connection betweenthe UE and the network exists. For various reasons, a UE may have tocamp on a different cell than the cell it is currently camped on. Whenin IDLE mode, this is achieved via “redirection”. When in CONNECTEDmode, this is achieved by performing a Handover procedure. For example,a UE may have to camp on a cell via which emergency services can beobtained.

At the IMS level, a Session Initiation Protocol (SIP) 380 response maybe received following an SIP INVITE request, Other SIP responses may bereceived in response to other SIP requests, including the SIP REGISTERrequest. Receipt of the SIP 380 may cause the UE to perform cellselection procedures in order to select a cell capable of performingemergency services. Alternatively or additionally, receipt of the SIP380 may cause the UE to perform an SIP emergency registration procedurein order to create a context suitable for establishing an emergency SIPsession. A SIP registration procedure involves transmission of a SIPREGISTER request.

In the present disclosure, all of these procedures are calledredirections, unless otherwise stated.

A 5G capable UE can access the 5G CN via New Radio (NR), E-UTRAN or viaa WLAN. The 5G CN accessed via a non-3GPP Access Network (AN) (forexample a WLAN) may differ from the 5G CN accessed via 3GPP AN (NR andE-UTRAN). The 5G CNs may be owned by different PLMNs, and possibly evenby PLMNs operating in different countries.

Emergency services are provided via any access, however they maypreferably be provided via a 3GPP AN. While the 5G CN does not provideaccess to the CS domain, it is possible that the UE is redirected to anE-UTRAN cell from an access network supported by the EPC network. TheEPC network offers CS Fallback (a UE performing CS Fallback makes a callusing CS procedures via the CS domain). Alternatively, the UE can accessthe CS domain by selecting a cell part of the GERAN, UTRAN or byselecting a cell supporting CS.

The CS emergency procedures require a UE to indicate the category ofemergency service requested. Examples of categories of emergency serviceare fire brigade, ambulance, police, Marine Guard, or Mountain Rescue. Acategory may be expressed in bits, as is described in greater detailbelow.

Likewise, the PS emergency procedures require a UE to indicate the typeof emergency service requested. Examples of types of emergency serviceare fire, ambulance, and police, amongst others. A type may be expressedusing Uniform Resource Names (URNs), as is described in greater detailbelow.

The type or category of emergency service is used, upon receipt by thenetwork, to select a Public Safety Access Point (PSAP).

Each country defines the types or categories of emergency servicesapplicable within that country. Consequently, each country may have adifferent set of types or categories of emergency services and may usedifferent emergency numbers to identify these types or categories ofemergency services.

For numbers in the second set, a call request via NR using 5G may bedetected as such by the P-CSCF in the IMS. The P-CSCF may send a SIPresponse message to the UE, for example in the form of an SIP 380response. Upon receipt, the 5G UE will now initiate (basic or emergency)call procedures. The 5G PLMN will have configured the UE with either: anindication for Emergency Services Support within a REGISTRATION ACCEPTmessage to the UE (the Emergency Services Support indication is validwithin the current Registration Area); or an Emergency Services Supportindicator in the Registration Area Accept message to indicate whetherthe UE can setup an emergency session (e.g. an emergency Protocol DataUnit (PDU) session) or the UE should perform a Service Requestprocedure. A Registration Area consists of one or more cells serving thesame PLMN. The network may inform the UE what the current RegistrationArea is. The network keeps track of the UE's current registration area.A location area or a tracking area are equivalent terms in differentsystems. In EPC, the UE performs NAS attachment or NAS tracking areaupdate procedures in order to inform the network of the tracking areathe UE is in.

A diagram of how messages may travel from a UE, through access networks,core networks, and domains before being received at a PSAP is shown withrespect to FIG. 1.

As seen in FIG. 1, a UE 101 may communicate with WLAN 102, NG 103,E-UTRAN 104, UTRAN 105, and GERAN 106. WLAN 102, NG 103, and E-UTRAN 104may communicate with 5G CN 107. E-UTRAN 104 and UTRAN 105 maycommunicate with EPC 108. UTRAN 105 and GERAN 106 may communicate withCS CN 109. 5G CN 107 and EPC 108 may communicate with PS 110, and fromPS 110 to IMS 111 and PSAP 112. CS CN 109 may communicate with CS 113and from CS 113 to PSAP 112.

If the UE is informed to perform a Service Request procedure upondetecting an emergency call, the network can redirect the UE (using aresponse message to the SERVICE REQUEST message) to a different system(for example, EPC) or to a different Radio Access Technology (RAT) (e.g.E-UTRAN connected to 5G CN). If redirected to the EPC, the UE may haveto initiate another Service Request procedure and the UE may beredirected to a cell supported by a CS CN as part of executing CSFallback procedures. A Service Request procedure comprises sending aService Request message.

The 5G CN may be supported by E-UTRAN or NR. Data connectionsestablished between the UE and the PS domain may be migrated from oneaccess network to another.

According to the prior art, a UE cannot be configured to detect that adialed number needs to be handled by a PSAP for which no servicecategory exists.

A user, dialing a number which is known to the serving PLMN to be fromthe second set of emergency numbers, may receive a SIP 380 response to afirst SIP INVITE request (the first SIP INVITE request including thenumber), the SIP 380 response including a Contact header field set to aURN. The URN may be a country specific URN. If the UE selects the PSdomain for a subsequent emergency call attempt, the UE can performemergency call procedures specific to the PS domain and include the URNin the subsequent SIP INVITE request.

A UE that is using the PS domain for call attempts and whose user dialsa number, known to the serving PLMN to be from the second set ofemergency numbers, may receive a SIP 380. If the UE selects the CSdomain, the UE may perform basic call setup procedures, conditionally.

In the S8 home routing architecture, a roaming UE connects to a P-CSCFin the Home PLMN (HPLMN). The P-CSCF in the HPLMN needs to beprovisioned with emergency numbers of the Visitor PLMN (VPLMN), orVPLMN's country. A configured P-CSCF can then detect the emergencynumbers that are applicable in the VPLMN's country or in the VPLMNitself.

FIG. 2 illustrates the roaming architecture for 3GPP access for homerouted traffic. While FIG. 2 is limited to the EPC architecture, it canbe appreciated that S8 can also be supported by different architecture,e.g. the architecture describing the 5G system, including the 5G CN. TheP-CSCF in the network architecture depicted in FIG. 2, is situated inthe “Operator's IP Services”.

As seen in FIG. 2, an HPLMN comprises a PDN Gateway 202, an HSS 210,PCRF 201, and the operator's IP services illustrated at 203. The VPLMNcomprises UTRAN 226 and GERAN 225. The VPLMN further comprises servinggateway 220, MME 221, and SGSN 224. UE 223 communicates with E-UTRAN222.

In NAS based provisioning, the UE may receive one or more numbersassociated with emergency service categories (known hereafter as“service categories”). The definition of service categories is definedin 3GPP Technical Specification (TS) 24.008 “Mobile Radio InterfaceLayer 3 specification; Core Network Protocols; Stage 3”, v. 15.0.1,September 2017, and is included below. The numbers provisioned orconfigured this way are part of the first set of emergency numbers. NASbased provisioning involves NAS messages. NAS messages, part ofprotocols used to interact with a CN (e.g. the EPC network, 5G CN, orGPRS CN), may include at least one Information Element (IE).

Section 10.5.3.13 of 3GPP TS 24.008 is reproduced below:

Section 10.5.4.33 of 3GPP TS 24.008 is reproduced below:

While NAS based provisioning (e.g. of numbers which are part of thefirst set of emergency numbers) takes place during e.g. NAS attachmentor NAS tracking area update procedures, the UE may receive a SIP 380response in response to an SIP INVITE with a Uniform Resource Identifier(URI) indicating a number from the second set. The SIP 380 response mayinclude a Contact header field with a URN. Depending on the URN, the UEmay be able to derive a service category, applicable to the CS domain,or the UE may not be able to derive a service category (in this case theURN is likely a Country specific emergency service URN). If the UEdecides to re-attempt the call on the CS domain, it either performsemergency call procedures (including a category in an EMERGENCY SETUPmessage) or basic call procedures (including the number in a SETUPmessage). If the UE decides to re-attempt the call on the PS domain, theUE performs an emergency call session setup, as described below, andincludes the URN received in a SIP INVITE request.

When the P-CSCF responds with an SIP 380 response, it may include a 3GPPIP Multimedia (IM) CN subsystem eXtensible Markup Language (XML) body inthis response. It may or may not include an indication indicating“emergency-registration”. This indication is a redirection, urging theUE to perform an initial emergency registration using a different VPLMN,if available.

The UE may perform an emergency call session setup in accordance withsubclauses 5.1.6.8, and 7.11.1 of 3GPP TS 24.229 “IP multimedia callcontrol protocol based on Session Initiation Protocol (SIP) and SessionDescription Protocol (SDP); Stage 3”, v. 15.0.0, September 2017, whichare reproduced below.

A Domain Name System (DNS) enables resolution of given input data to oneor more output data, by for example resolving domain names to one ormore IP addresses, or resolving domain names to one or more NamingAuthority Pointer (NAPTR) records. A DNS consists of a DNS client and aDNS server. A DNS client may be provided as part of, or within a UE. ADNS client sends data to be resolved in a DNS request message to a DNSserver. A DNS server, when receiving a DNS request from a DNS client,may respond to the DNS request with a DNS response that contains aresolution of the requested data or may provide the address of anotherDNS server to which the DNS client should resend its DNS request. Inproviding a response that contains a resolution of the requested data,the DNS server may use configuration that it has access to, send one ormore DNS requests to one or more other DNS servers or use data from acache (i.e. data previously received from other DNS servers that is notknown to be stale).

A UE, in order to be able to provide DNS client functionality, needs tobe configured with one or more DNS server addresses such as InternetProtocol version 4 (IPv4) addresses, and Internet Protocol version 6(IPv6) addresses, amongst others. A UE may receive a DNS server's IPaddress when it requests connectivity with a data network, like a PacketData Network (PDN) or others. The DNS server's IP address is returned bythe network. Typically, the DNS server's IP address is included in theProtocol Configuration Options (PCO) Information Element (IE). The PCOIE is delivered to the UE in an NAS message.

A DNS server operated by the PLMN offering emergency services should betrustable, meaning that neither the DNS server is expected to becompromised nor the DNS requests and responses are expected to becompromised while in transit between DNS server and UE.

A DNS server's IP address is typically configured when the UE connectsto the entry point, like a PDN GW or UPF of the data network, such as adata network that hosts the IMS. This entry point may be in the VPLMN orin the HPLMN. In S8, the entry point is in the HPLMN.

The Global System for Mobile Communications (GSM) Association (GSMA)runs a database whereby PLMN operators can exchange data that allowsthem to provide roaming for their subscribers to each other's PLMNs. Thedatabase is useful for updating other PLMNs about static data, whichincludes emergency numbers and categories in a 5-bit format. Thisdatabase is called the NG RAEX IR.21 Database. Therefore, sinceemergency numbers and categories is not very dynamic, data from thisdatabase can be extracted and configured in the HPLMN P-CSCF in order todetermine emergency numbers in the first set that can be recognized asemergency numbers in a roaming user's VPLMN, if detected in a SIPINVITE.

As part of PS emergency call procedures the UE often needs to perform anIMS emergency registration procedure. As part of the IMS emergencyregistration procedure the UE transmits an SIP REGISTER requestcontaining an “sos” SIP URI parameter in the Contact header field.

A P-CSCF receiving this SIP REGISTER request may respond with a 420 (BadExtension) or a 403 (Forbidden) response. The P-CSCF may include a 3GPPIM CN subsystem XML body in this response. If the network supports anemergency session for an unregistered user, the P-CSCF may furtherinclude an indication indicating “anonymous-emergencycall”.

GPRS and EPS support delivery of emergency numbers and categories duringthe NAS attachment or e.g. NAS tracking area update procedures. Theadvantage of delivering this information during these procedures is thata UE can know whether an emergency number is dialed immediately aftersuccessful network attachment. The equivalent of the NAS attachment ore.g. NAS tracking area update procedures in 5G are herein called the 5Gregistration procedures. The 5G registration procedures include the UEsending a REGISTRATION REQUEST message and the UE receiving e.g. aREGISTRATION ACCEPT message.

While the present disclosure aims to provide a solution that applies toany access technology, 5G specific solutions may still be needed inaddition. For example, to prevent situations of race conditions, wherethe UE is able to initiate voice calls after successful 5G registration,but before the UE has received the emergency information via anotherprotocol, such as DNS. In this period of time a number would not bedetected as an emergency number by the UE.

A P-CSCF in general is not aware of the emergency numbers, categories ortypes in use in a VPLMN. For S8, a P-CSCF in the HPLMN needs to detectwhether a number is in the second set for the VPLMN or the VPLMN'scountry. The NG RAEX IR.21 Database doesn't provide this information.

Alternatively or additionally, a VPLMN should be able to perform NASprocedures to configure the UE with numbers from the second set.

The NG RAEX IR.21 Database does not provide sufficient information tothe P-CSCF. For example, there is no indication that the UE must make abasic CS basic call if a SIP 380 response is received for a SIP INVITE.There is no information that would allow a UE to retry the emergencycall on PS domain, using a Country specific emergency service URN.

The SIP 380 response can further include one of the two the followingoptional indications: “emergency registration” or“anonymous-emergencycall”. The NG RAEX IR.21 Database does not allow theVPLMN to inform the HPLMN that it's P-CSCF needs to include such anindication or not.

The IMS (e.g. the P-CSCF) supported by 5G CN may detect that a SIPINVITE contains an emergency number. The P-CSCF may reject the SIPINVITE with a SIP 380 response, as discussed above, or the P-CSCF mayaccept the SIP INVITE, indicating in a response to the UE that the SIPINVITE was for emergency services. If a session results from the SIPINVITE, the session is considered an emergency session. However, theemergency services session is not using a bearer dedicated for emergencyservices.

Where the target RAT, for example NR, is unsuitable for emergencyservices, a bearer with the emergency session should remain on thesource RAT (just like the emergency bearer would). Since the AMF ascurrently specified in 3GPP TS 23.501, “System Architecture for the 5GSystem; Stage 2”, v. 15.0.0, December 2017, is unaware that a sessionconsidered an emergency session is using a normal, non-emergency bearer,this session may be migrated or handed over to the RAT unsuitable foremergency services.

It may be undesirable to hand over an emergency session using anon-emergency bearer to a RAT that does not support emergency services.

The present disclosure presents solutions to the above problems withreferences to examples or embodiments which are not absolute and textualconstructs or IEs are for illustrative purposes. Other IE layout orother domain name label orderings could be possible and are within thescope of the present disclosure. Furthermore, some embodiments describedherein may be combined with other embodiments without departing from thescope of the present disclosure.

The present disclosure provides solutions that aim to provision the UEwith emergency information. Emergency information consists of emergencynumbers, URNs, categories, or indications. For each emergency numberthere is one or more of the following: a URN (e.g. suitable for the PSdomain); a category (e.g. suitable for the CS domain); or an indicationthat the UE needs to use basic call procedures on the CS domain.

Alternatively, the indication that the UE use basic call procedures onthe CS domain can be an indication that the UE use emergency callprocedures on the PS domain only, an indication that the UE useemergency session procedures on PS domain only, or an indication thatthe UE use emergency procedures on PS domain only.

The emergency information provisioned to the UE can be considered valid.Valid emergency information can be used by the UE when comparing dialednumbers or digits with provisioned emergency numbers (e.g. part of theemergency information) in order to detect if a dialed number is anemergency number.

When a (e.g. dialed) number is an emergency number, the UE invokesdomain specific emergency call setup procedures or invokes basic CS callsetup procedures, depending on the domain selected and depending on theemergency information.

When using E-UTRAN, the UE may perform CS fallback procedures (for basiccall) or indicate CS fallback for emergency call during the CS fallbackprocedures. If the emergency information indicates the UE needs toinvoke basic CS call setup procedures, the UE performs CS fallbackprocedures, without indicating CS fallback for emergency call.

A VPLMN's network servers, including but not limited to MME, AMF,Serving GPRS Support Node (SGSN) or DNS servers, may maintain aconfiguration indicating per country code, such as a Mobile Country Code(MCC), or per VPLMN:

-   -   a first value indicating the country where the type of emergency        service is deployed or a second value uniquely identifying the        type of emergency service in the country where the type of        emergency service is deployed. The first value (e.g. xy) and the        second value (e.g. 567) allow a URN such as        “urn:service:sos.country-specific.xy.567” to be constructed, as        discussed with reference to 3GPP TS 24.229.    -   a value representing a 5-bit Service Category value or the 5-bit        Service Category value itself, as discussed with reference to        3GPP TS 24.008;    -   whether the call should be setup on the CS domain instead of the        PS domain (using IMS);    -   whether basic call procedures or emergency call procedures        should be used in the CS domain; or    -   whether the P-CSCF should send a particular SIP response to the        UE and whether the SIP response should include        “emergency-registration” or “anonymous-emergencycall”.

Re-Purposing Category Values

The NAS signalling to the UE provides 5 bits to the UE, providing for2⁵=32 possibilities. Few of these bit combinations have been reserved.Most PLMNs would set one of the five bits to identify one of thecategories of emergency services supported in the country. In somecountries, combinations are possible. For example, if more than one bitis set to 1, routing to a combined emergency center, such as anambulance and fire brigade in Japan, is required.

That still leaves most possible combinations of the 5 bits unused.

These unused combinations can be used to encode emergency servicespreviously not expressed in the service category. This could enableusage of CS emergency call procedures for emergency services previouslybeing handled via basic call procedures on the CS domain.

On the PS domain, UE modifications are needed to derive a URN from thesenew combinations. However, at least some UEs, which are alreadydeployed, cannot be modified.

Provisioning P-CSCF with Emergency Information Obtained from a Databaseof Roaming Related Data

At present the P-CSCF can be provisioned with emergency URNs, but thereis no simple, reliable, secure, or scalable way to obtain them fromVPLMNs. Specifically, PLMN operators have to contact all of theirroaming partner PLMN operators to share or request necessary data.

Therefore, this solution aims to enable HPLMN operators to provisiontheir network (e.g. P-CSCFs or DNS servers, amongst others) with theirroaming partner VPLMN's emergency URNs (including country-specific URNs)by enabling VPLMN operators to put into a database the necessary data toenable roaming partners and HPLMN operators to configure their P-CSCFsor DNS server (as used in IMS S8HR roaming). This data may comprise:

-   -   a first value indicating the country where the type of emergency        service is deployed or a second value uniquely identifying the        type of emergency service in the country where the type of        emergency service is deployed;    -   a value representing a 5-bit Service Category value or the 5-bit        Service Category value itself;    -   an indication of whether the call should be setup on the CS        domain instead of the PS domain (using IMS) and whether basic        call procedures or emergency call procedures should be used in        the CS domain; or    -   an indication that the P-CSCF should send a particular SIP        response to the UE and whether the SIP response should include        “emergency-registration” or “anonymous-emergencycall”.

A P-CSCF may either query the roaming database or DNS or maintainconfiguration information indicating per country code (e.g. MCC) or perVPLMN:

-   -   whether to include “emergency-registration” or        “anonymous-emergencycall” in a SIP response;    -   whether to include a URN in the SIP response's Contact header        field and which URN to include.

A HPLMN DNS server may maintain configuration information indicating percountry code (e.g. MCC) or per VPLMN:

-   -   a portion of a URN. For country specific URNs, the portion of a        URN could include a first value indicating the country where the        type of emergency service is deployed or a second value uniquely        identifying the type of emergency service in the country where        the type of emergency service is deployed. For other cases, such        as a URN according to Request For Comment (RFC) 5031, “A Uniform        Resource Name (URN) for Emergency and Other Well-Known        Services”, January 2008, the portion of a URN could be, for        example, “sos.police” from the URN “urn:service.sos.police;    -   a value representing a 5-bit Service Category value or the 5-bit        Service Category value itself;    -   an indication of whether the call should be setup on the CS        domain instead of the PS domain (using IMS) and whether basic        call procedures or emergency call procedures should be used in        the CS domain; or    -   an indication that the P-CSCF should send a particular SIP        response to the UE and whether the SIP response should include        “emergency-registration” or “anonymous-emergencycall”.

Alternatively, if the information is available via a DNS query from theHPLMN P-CSCF, the P-CSCF may obtain the information by querying a VPLMNDNS server with a Fully Qualified Domain Name (FQDN) including a PLMNcode or an MCC code.

Mappings as described below between 5-bit service categories and domainnames or FQDNs may apply, with the clarification that a hostname is astring of alphanumeric values. The alphanumeric values can be obtainedfrom a roaming database or DNS server as part of the emergencyinformation. The P-CSCF or DNS may obtain the alphanumeric values fromthe roaming database.

Prevent Handing Over Connections within which there is an EmergencySession

In order for a network to prevent handing over connections within whichthere is an emergency session, the network is informed by the IMS(including the P-CSCF that accepted the emergency session) that theconnection has an emergency session. The network may then preventredirecting or handing over a connection that has an emergency sessionto a RAT or CN that doesn't support emergency sessions.

Provisioning the UE with Emergency Information

While the present disclosure describes DNS and NAS provisioning methods,other methods may also apply including Access Network Query Protocol(ANQP), Internet Key Exchange Version 2 (IKEv2), Dynamic HostConfiguration Protocol (DHCP), and HyperText Transfer Protocol (HTTP).The above list of methods is not intended to be limiting.

Examples of request and response protocols are shown with respect toFIG. 3. The response may include an emergency document. An emergencydocument is considered emergency information. An emergency document mayencode the emergency information in XML (eXtended Markup Language). Thisdocument includes other examples of encoding emergency information, e.g.in IEs or in domain names or in strings or in labels. A domain name, ahost name, or a label are all considered strings. A string is notlimited to be being a domain name, a host name, or a label. A domainname may include one or more hostnames. A domain name or a hostname arealso considered labels. A URN may include labels.

As seen in FIG. 3, UE 301 may communicate with a network node 303through IMS 302. As illustrated by arrow 330, a request is transmittedto the network node 303 for an emergency document and the emergencydocument is returned to the UE 301, as illustrated by arrow 340. Therequest may be an HTTP GET message, a DNS request, or a DHCP request,and include location information.

5G

When using a 3GPP access and a non-3GPP access to access the 5G CN, theUE may register with different PLMNs via each access. This typicallymeans the UE is using different core networks. Typically, a PLMN runsits own core network.

When the UE receives emergency information from the AMF in response to aREGISTRATION REQUEST message sent by the UE, the UE can use thisinformation to find a match between a (e.g. dialed) number and anemergency number in the emergency information. Each emergency number,within the emergency information, is associated with at least one of acircuit switched emergency (CSE) call indicator, Emergency ServiceCategory Value, URN for emergency service, or country-specific emergencyURN. A URN for emergency service or a country-specific emergency URN isconsidered an emergency URN.

The UE may reconstruct the (country-specific) emergency URN (foremergency service) from the received emergency information. For example,the last hostname of a country-specific emergency URN may have digitsthat are the same as the emergency number's digits or, the last hostnameof a country-specific emergency URN may have characters that do notnecessarily equate to the emergency number's digits. If the emergencyURN is not a country-specific emergency URN, the emergency URN can bederived from the Emergency Service Category Value. For example,urn:service:sos.police can be derived from an Emergency Service CategoryValue with only the first bit set. The emergency information receivedmay include an indication indicating whether the emergency URN is to bederived from the Emergency Service Category Value.

Depending on the domain selected, the UE performs PS emergency callprocedures or CS procedures. Depending on the value of the CSE, the CSprocedures consist of CS emergency call procedures or CS basic callprocedures. If the UE performs PS emergency call procedures, the UE mayinclude the emergency URN in a SIP INVITE message. If the UE performs CSemergency call procedures, the UE may include the Emergency ServiceCategory Value in an EMERGENCY SETUP message. If the UE performs CSbasic call procedures, the UE may include the dialed digits in a SETUPmessage.

One 5G CN

When using the E-UTRAN, NR, or WLAN to access the 5G CN, the UE may needto register to obtain services. The UE registers by transmitting aREGISTRATION REQUEST message. In response to the registration requestthe UE may receive emergency information including e.g. a list with oneor more emergency numbers, associated categories, associated URNs, anindication that a call to the number triggers emergency procedures onthe PS domain only, or an indication that a call to the number triggersbasic procedures on the CS domain. The emergency information received aspart of NAS registration procedures

The UE also sends the registration request periodically, for example, toupdate registration information held by the 5G CN. In response to theseregistration requests, the UE may receive the list with one or moreemergency numbers mentioned above. If the UE receives an empty list(i.e. a list of size zero), the UE may either replace a previouslystored list with an empty list or the UE may ignore the empty list. Ifthe UE receives no list, the UE may not overwrite a previously receivedlist.

Replacing a previously received list with an empty list is useful whenthe UE registers with a PLMN in the same country, and this PLMN handlesall emergency call detection in the network, beyond what is detected dueto Mobile Entity (ME) hard coded numbers and Universal SubscriberIdentity Module (USIM) provisioned numbers.

Two 5G CNs

When using the E-UTRAN or NR to access the 5G CN and when using the WLANto access another 5G CN, the other 5G CN may be part of a differentPLMN. The other 5G CN may even be situated in a different country.

The same may occur when the UE accesses EPC via 3GPP access and non-3GPPaccess. A UE accessing EPC via 3GPP access may receive a policyindicating whether a UE may consider emergency information received vianon-3GPP access.

Further, emergency information received via non-3GPP access may also beassociated with country information, such as an MCC. The countryinformation identifies the country for which the emergency informationis valid. Valid emergency information can be used when comparing dialednumbers with provisioned emergency numbers, in order to detect if adialed number is an emergency number.

One 5G CN and One Non-5G CN

When using E-UTRAN or NR to access the 5G CN and when using the WLAN toaccess an EPC, the EPC may be part of a different PLMN. The other EPCmay even be situated in a different country.

The same considerations as in the case of two 5G CNs apply here, withthe clarification that one of the two CNs is a non-5G CN.

Last Hostname Consists of Characters

The Emergency Information IE proposed below is included in a response tothe UE's request to register with the network, such as, but not limitedto, a 5G CN. The Emergency Information IE contains information toreconstruct a country-specific emergency URN (e.g.“urn:service:sos.country-specific.XY.567”. The portions “sos”,“country-specific”, “XY”, “567” are considered labels. A labels consistsof one or more characters. The characters allowed in a hostname aretypically also those allowed in a label). The last label, e.g. “567”,need not consist of characters that match the number digits in theemergency number. If they do not match, the “length of the emergencylabel” field indicates the number of octets occupied by the subsequentcharacters. The characters may be encoded in accordance with a codingscheme. The characters represent the characters of the last label. Whenthe “length of the emergency label” field is set to 0 or the emergencyinformation received includes an indication indicating that the URN is acountry specific URN, the number of digits in the Emergency InformationIE represent the characters of the last label, for example “567”. TheCountry Characters in the Emergency Information IE represent thecharacters of the penultimate label, for example “XY”. The label orfirst sub-service “country-specific” and the label or top-level service“sos” complete the hostname. The country specific URN is reconstructedby prepending these labels with “urn:service:”.

The Emergency Information IE contains coding scheme information. Wherethe encoding scheme is GSM default alphabet, language unspecified,defined in 3GPP TS 23.038, “Alphabets and language-specificinformation”, v. 14.0.0, March 2017, the proposed IE below has limitedthe allowable characters to those that can be encoded in 7 bits.Alternatively, a 16 bit encoding could be chosen, for example UniversalCoded Character Set (UCS-2), requiring each character to occupy 2consecutive octets.

Emergency Information IE

The purpose of this information element is to encode emergencyinformation for use within the country indicated within the IE.

The Emergency Number List information element is coded as shown below.The Emergency Number List IE may be a type 4 information element. Noupper length limit is specified except for that given by the maximumnumber of octets in an L3 message, as provided in 3GPP TS 44.006,“Mobile Station-Base Station System (MS-BSS) interface; Data Link layerspecification”, v 14.0.0, March 2017.

Last Hostname Consists of Numbers Matching the Dialed Digits

The Emergency Information IE proposed below is included in a response tothe UE's request to register with the 5G CN. The Emergency InformationIE contains enough information to reconstruct a country-specificemergency URN (for example “urn:service:sos.country-specific.XY.567”),if the emergency information received includes an indication indicatingthat the URN is a country specific URN. The number of digits in theEmergency Information IE represent the characters of the last label,e.g. “567”. The Country Characters in Emergency Information IE representthe characters of the penultimate label, e.g. “XY”. The label“country-specific” and the label “sos” complete the hostname. Thecountry specific URN is reconstructed by prepending this hostname with“urn:service:”.

The Emergency Information IE contains coding scheme information. Wherethe encoding scheme is GSM default alphabet, language unspecified,defined in 3GPP TS 23.038, the proposed IE below has limited theallowable characters to those that can be encoded in 7bits, with thelast 2 bits set to 10. Alternatively, the bits could be set to force thecharacters to be lower case characters. Alternatively, the last 2 bitsof the 7 do not need to be hardcoded. Alternatively, a 16 bit encodingcould be chosen (for example, UCS2). Requiring each character to occupy2 consecutive octets.

The purpose of this information element is to encode emergencyinformation for use within the country indicated within the IE.

The Emergency Number List information element is coded as shown below.The Emergency Number List IE is a type 4 information element. No upperlength limit is specified except for that given by the maximum number ofoctets in a L3 message (see 3GPP TS 44.006).

A Second IE with Emergency Information Complementing the EmergencyNumber List IE

The Emergency Information IE proposed below is included in a response tothe UE's request to register with the CN or in a response to the UE'srequest to (update location information (for non-5G CN), tracking areainformation (for non-5G CN: EPC network), or) registration areainformation with the CN. The Extended Number List IE may also be knownas the Emergency Information IE or by an otherwise named IE. TheEmergency Information IE contains enough information to reconstruct acountry-specific emergency URN (e.g.“urn:service:sos.country-specific.XY.567”).

The Emergency Information IE contains coding scheme information. Wherethe encoding scheme is GSM default alphabet, language unspecified,defined in 3GPP TS 23.038, the proposed IE below has limited theallowable characters to those that can be encoded in 7bits, with thelast 2 bits set to 10. Alternatively, the bits could be set to force thecharacters to be lower case characters. Alternatively, the last 2 bitsof the 7 do not need to be hardcoded. Alternatively, a 16 bit encodingcould be chosen (e.g. UCS2), requiring each character to occupy 2consecutive octets.

The “length of the emergency label” field indicates the number of octetsoccupied by the subsequent characters. The characters may be encoded inaccordance with a coding scheme. The characters represent the charactersof the last label.

The emergency numbers in the Emergency Number List IE are intended tocorrespond with the labels in the Emergency Information IE: the 1stEmergency Number information digits correspond to the 1st URI's lastemergency label. If the Length of 1st URI's last emergency label is setto 0 or the emergency information received includes an indicationindicating that the URN is a country specific URN, the last label of thecountry-specific URN matches the number digits in the emergency numberin the Emergency Number List IE. If the Length of 1st URI's lastemergency label is set to non-zero, the last label of thecountry-specific URN matches the label characters.

The Country Characters in Emergency Information IE represent thecharacters of the penultimate label, e.g. “XY”. The label“country-specific” and the label “sos” complete the hostname. Thecountry specific URN is reconstructed by prepending this hostname with“urn:service:”.

The purpose of this information element is to encode emergencyinformation for use within the country indicated within the IE.

The Emergency Number List information element is coded as shown below.

The Emergency Number List IE is a type 4 information element. No upperlength limit is specified except for that given by the maximum number ofoctets in a L3 message (see 3GPP TS 44.006).

Other CNs

A UE attempting to use the services provided via non-5G CNs accessed via3GPP access, often also registers with the CN. The UE registers bytransmitting an NAS attach request message, an NAS tracking areaupdating request message or a NAS location area request updating messageto the CN. NAS messages, part of protocols used to interact with a CN(e.g. the EPC network, 5G CN, or GPRS CN), may include at least oneInformation Element (IE). In response to the attach request message, thetracking area updating request message, or the location area request theUE may receive a list with one or more emergency numbers, associatedcategories, associated URNs, or:

-   -   an indication that a call to the number triggers emergency        procedures on PS domain only; or    -   an indication that a call to the number triggers basic        procedures on CS domain.

While some existing CNs already provide some emergency information viaNAS messages, the NAS messages could be extended to provide the missing,additional emergency information. The extension of an NAS message'scontent would be backwards compatible, while providing an evolution to5G. Furthermore, extension would prevent duplication. It should be notedthat NAS messages can only include a limited number of octets encodinginformation in general, including emergency information in particular.

When the UE receives emergency information from the mobility managementnetwork element (for example, MME, SGSN, evolved Packet Data Gateway(ePDG)) in response to a registration message (for example, an attachmessage, location area update message, tracking area update message,IKE, Extensible Authentication Protocol (EAP), amongst others) sent bythe UE, the UE can use this information to find a match between a dialednumber and an emergency number in the emergency information. Eachemergency number, within the emergency information is associated with atleast one of a circuit switched emergency (CSE) call indicator,Emergency Service Category Value, or country-specific emergency URN.

The UE may reconstruct the country-specific emergency URN from thereceived emergency information. For example, the last hostname of acountry-specific emergency URN may have digits that are the same as theemergency number's digits or, the last hostname of a country-specificemergency URN may have characters that do not equate to the emergencynumber's digits.

Depending on the domain selected, the UE performs PS emergency callprocedures or CS procedures. Depending on the value of the CSE, the CSprocedures consist of CS emergency call procedures or CS basic callprocedures. If the UE performs PS emergency call procedures, the UEincludes the reconstructed country-specific emergency URN in a SIPINVITE message. If the UE performs CS emergency call procedures, the UEmay include the Emergency Service Category Value in an EMERGENCY SETUPmessage. If the UE performs CS basic call procedures, the UE may includethe dialed digits in a SETUP message.

Since existing registration response messages already include theEmergency Number List IE, it is proposed to extend the (NAS)registration response with the Emergency Information IE proposed. TheExtended Number List IE may also be known as the Emergency InformationIE.

DNS-Based Solution Overall Procedure

While 5G is a newly defined system, other systems, for example systemssupporting the EPC, are currently deployed. In 5G the emergencyinformation can be provided as part of the NAS, but in the othersystems, upgrading the MME and the UE's NAS as well as the UE's upperlayers (which may comprise, for example, an IMS client) is not asstraight-forward.

This solution is also applicable to CNs other than 5G CNs. The UE needsto obtain emergency information with one or more emergency numbers,associated categories, associated URNs, and/or:

-   -   an indication that a call to the number triggers emergency        procedures on PS domain only; or    -   an indication that a call to the number triggers basic        procedures on CS domain.

Any provisioning mechanism used to provide the list should preferably beeasily deployable. For example, a DNS server can be used to obtain thelist. A UE can query a DNS without impacting the NAS layer, for example.The UE may obtain, from a DNS server whose address is indicated by thePLMN's network, as DNS servers obtained from untrusted WLAN areconsidered untrusted DNS servers, a list of emergency information asdescribed above. The list may contain hostnames. Some hostnames mayrepresent emergency information, for example because of the presence ofa label like the “sos” label. Some information in the emergencyinformation may be one or more hostnames formatted as described ingreater detail below.

This solution would at least partially prevent the situation where theUE doesn't detect that a dialed number is in the second set of emergencynumbers.

If the UE receives an empty list, the UE may either replace a previouslystored list with an empty list (i.e. remove/delete the current list) orthe UE may ignore the empty list. If the UE receives no list, the UE maychoose to not overwrite a previously received list. Replacing apreviously received list with an empty list is useful when the UEregisters with a PLMN in the same country as the HPLMN, and this PLMNhandles all emergency call detection, beyond what is detected due to MEhard coded numbers and USIM provisioned numbers, in the network (e.g. bymeans of a SIP 380 response from the P-CSCF or, in the MSC, by routingthe basic call request to a PSAP).

When using DNS to obtain this list, the UE may perform a DNS NAPTR queryusing an indicator by sending a DNS request to one or more previouslyconfigured DNS servers. The UE may, for example, send a stringindicating that it wishes to receive a list of emergency information asdescribed above. The string may be a domain name or FQDN. The DNS servermay then respond with a DNS response message that may containreplacement records.

The replacement records, if present in the DNS response message, containdomain names (a domain name can be a set of dot separated host names ora set of dot separated labels) or FQDNs.

The Internet standards (Requests for Comments) for protocols mandatethat component hostname labels may contain only the ASCII letters ‘a’through ‘z’ (in a case-insensitive manner), the digits ‘0’ through ‘9’,and the hyphen (‘-’). The original specification of hostnames in RFC952, “DOD Internet Host Table Specification”, October 1985, mandatedthat labels could not start with a digit or with a hyphen, and must notend with a hyphen. However, a subsequent specification, RFC 1123,“Requirements for Internet Hosts—Application and Support”, October 1989,permitted hostname labels to start with digits. No other symbols,punctuation characters, or white space are permitted.

When mapping 5 bit category information to a valid host name or domainname's label, simply taking the first or last five bits of an ASCII orUTF-8 character could result in ASCII or UTF-8 characters that are notallowable in a hostname or label, according to the hostname requirementabove. For example, hexadecimal 1B represents the ESC command in ASCII.Therefore, solutions are provided for this problem below.

The above DNS procedure can be used over any IP access that is providedby any access technology, including for example, WLAN, and it is notlimited to LTE access or EPC nor NR access or 5GCN, or the like.

As an alternative to a UE, a P-CSCF could interrogate a DNS server toobtain such information.

In all of the alternatives below, in order to ensure the constructeddomain name is unique, and does not overlap another domain name alreadyreserved for example through ICANN, a top-level domain name could beadded. For example, eservicecat.mnc<MNC>.mcc<MCC>.pub.3gppnetwork.org,where <MNC> and <MCC> are the E.212 Mobile Network Code and MobileCountry Code of the PLMN providing the IMS PDN, which is either theHPLMN or the VPLMN, dependent upon whether Local BreakOut (LBO) orhome-based routing (S8HR) roaming is used).

Alternatively, the following domain name could be considered“sos.en.cn.mcc<MCC>.pub.3gppnetwork.org”. The top-level domain name toappend to the constructed domain name could be static, well known,pre-provisioned or hard coded, or could be provisioned in the UE at timeof SIP registration (for example, received in a SIP response to a SIPINVITE request) or at PDN connection set-up, for example using the PCOIE in NAS messaging, using DHCP, using Open Mobile Alliance (OMA) DeviceManagement (DM), amongst others. Alternatively, the UE could derive thetop-level domain name to append to the constructed domain name from aconfigured IMS home network domain name, as described in 3GPP TS 23.003,“Numbering, addressing, and identification”, v. 15.2.0, December 2017,and insert the label “pub” before the labels “3gppnetwork.org” in orderto ensure the UE can derive the resultant domain name or FQDN.

Note: if a P-CSCF rather than a UE is initiating the DNS request, theinsertion of the label “.pub” is unnecessary.

Mapping 5-Bit Service Categories to and from Domain Names or FQDNs

Alternative 1

In one embodiment, each bit that is “on” or “set” could be mapped to aletter, as shown by the example of Table 2 below. A bit that is not setor “off” could be mapped to another valid hostname character, forexample to ‘z’ or ‘0’ (zero) or ‘o’ or ‘-’. Mapping to a letter may bepreferred for DNS servers not permitting a hostname to start with adigit or a dash.

TABLE 2 Example mapping of bits to letters Bit Emergency service Letter1 Police ‘p’ 2 Ambulance ‘a’ 3 Fire Brigade ‘f’ 4 Marine Guard ‘g’ 5Mountain Rescue ‘r’

Alternatively, the hostname could start with some predefined characters,for example “cat”. For example, if the 5-bit service category is‘01100’, the hostname might be “cat0af00”, or, when reading right toleft, “cat00af0”.

Instead of mapping to a letter such as ‘p’, ‘a’, ‘f’, ‘g’, or ‘r’, eachbit that is “on” or “set” could be mapped to a digit. Using the sameexample of 5-bits ‘01100’, the mapped hostname could be “cat01100”, orwhen reading right to left, “cat00110”.

Alternative 2

The service category can be described in digits, for example,hexadecimals or decimals. Currently, 2⁵=32 service category valuesexist. Any digits between and including [0-31] would represent a validservice category. In hexadecimals, any hexadecimals between andincluding [0-1F] would represent a valid service category. For example,a service category value with the bits representing “Ambulance” and“Fire Brigade” set could be represented by “06”, or “cat06”.

Alternative 3

Alternative 3 is combined with alternative 1 or alternative 2 andimproves these alternatives as follows.

In order to indicate that a call on the CS domain should be performedusing basic procedures, the predefined characters could be followed byan empty string, e.g.: “cat”.

On the other hand, “e” or “ec” or “ecsc” could be considered analternative set of predefined characters, representing “emergency”,“emergency call” or “emergency CS call”, respectively. If the networkwishes to indicate that the call on the CS domain should be performedusing basic call procedures (i.e. not emergency call procedures), thepredefined characters could be “c” or “csc”. While “e” or “ec” or “ecsc”would be followed with a category representation (see e.g. alternative 1or alternative 2), “c” or “csc” would not be followed by a categoryrepresentation.

Therefore, using the examples above and where the (<MNC> or) <MCC> ofthe network providing the IMS PDN are for example 15 and 234,respectively, the following URNs categories would be transposed into theassociated domain names or FQDNs. It should be noted that this list isfor illustrative purposes only and is not intended to be an exhaustivelist of all possibilities.

-   -   cat0af00.eservicecat.mnc015.mcc234.pub.3gppnetwork.org    -   cat00af0.eservicecat.mnc015.mcc234.pub.3gppnetwork.org    -   cat01100.eservicecat.mnc015.mcc234.pub.3gppnetwork.org    -   cat00110.eservicecat.mnc015.mcc234.pub.3gppnetwork.org    -   06.eservicecat.mnc015.mcc234.pub.3gppnetwork.org    -   cat06.eservicecat.mnc015.mcc234.pub.3gppnetwork.org        Mapping Emergency URNs to and from Domain Names or FQDNs

Two emergency URN sets exist.

-   -   a first emergency URN set: “urn:service:sos”,        “urn:service:sos.police”, “urn:service:sos.ambulance”,        “urn:service:sos.fire”, “urn:service:sos.marine”, and        “urn:service:sos.mountain”; and    -   a second emergency URN set consisting of other URNs, known as        Country specific emergency service URNs.

By dropping the prefix text of “urn:service:” from the URNs in the setsas defined above, and then reversing order of the remaining hostnamelabels, a domain name or FQDN can be constructed. However, in order toensure the constructed domain name is unique and does not overlapanother domain name already reserved, for example through ICANN, atop-level domain name could be added. For example, a URN could beconstructed such as service.urn.mnc<MNC>.mcc<MCC>.pub.3gppnetwork.org,where <MNC> and <MCC> are the E.212 Mobile Network Code and MobileCountry Code of the PLMN providing the IMS PDN, which could be eitherthe HPLMN or the VPLMN, dependent upon whether LBO or S8HR roaming isused.

Alternatively, the following domain name could be considered“sos.en.cn.mcc<MCC>.pub.3gppnetwork.org”. The top-level domain name toappend to the constructed domain name could be static, well known,pre-provisioned or hard coded or could be provisioned in the UE at timeof SIP registration, for example received in a SIP response to a SIPINVITE request, or at PDN connection set-up, for example using the PCOIE in NAS messaging, using DHCP, using OMA DM, amongst others.Alternatively, the UE could derive the top-level domain name to appendto the constructed domain name from a configured IMS home network domainname, as described in 3GPP TS 23.003, and insert the label “pub” beforethe labels “3gppnetwork.org” in order to ensure the UE can derive theresultant domain name or FQDN.

Note: if a P-CSCF rather than a UE is initiating the DNS request, theinsertion of the label “.pub” is unnecessary.

Therefore, using the examples above and where the <MNC> and <MCC> of thenetwork providing the IMS PDN are 15 and 234, respectively, thefollowing URNs would be transposed into the associated domain names orFQDNs:

-   -   sos.service.urn.mnc015.mcc234.pub.3gppnetwork.org    -   police.sos service.urn.mnc015.mcc234.pub.3gppnetwork.org    -   ambulance.sos service.urn.mnc015.mcc234.pub.3gppnetwork.org    -   fire.sos.service.urn.mnc015.mcc234.pub.3gppnetwork.org    -   marine.sos.service.urn.mnc015.mcc234.pub.3gppnetwork.org    -   mountain.sos.service.urn.mnc015.mcc234.pub.3gppnetwork.org

The above may correspond to the following text to be added to 3GPP TS23.003.

Alternatively, the replacement forms above could include the label named“visited-country”, i.e.:<ps-emergency-type>.<cs-emergency>.<emergency-number>.sos.en.cn.mcc<MCC>.visited-country.pub.3gppnework.org.

The “emergency number FQDN based on the Emergency Numbers FQDN format asspecified in 3GPP TS 23.003”, referred to above may be based on addingthe following sections to 3GPP TS 23.003.

When a UE receives e.g.“sos.ambulance.cs.15.sos.en.cn.mcc345.pub.3gppnetwork.org” or“sos.police.ecs00001.17.sos.en.cn.mcc345.pub.3gppnetwork.org” and itdetects a dialed number matching:

-   -   15: the UE can derive from        “sos.ambulance.cs.15.sos.en.cn.mcc345.pub.3gppnetwork.org” that        numbed 15 matches the “emergency-number” portion. Further, the        value of the “cs-emergency” portion is “CS”. The value “CS”        indicates that the UE must perform CS basic call procedures if        the UE selects the CS domain to make the call. The value of        “ps-emergency-type” portion is “sos.ambulance”. The value        “sos.ambulance” indicates that the UE must include a constructed        URN in the SIP INVITE if the UE selects the PS domain to make        the call or emergency session. The UE constructs a URN by        prepending “urn:service:” to the value, resulting in the        constructed URN “urn:service:sos.ambulance”.    -   17: the UE can derive from        “sos.police.ecs00100.17.sos.en.cn.mcc345.pub.3gppnetwork.org”        that numbed 17 matches the “emergency-number” portion (see Table        19.4.2.9A.x-1). Further, the value of the “cs-emergency” portion        is “ecs00001”. The value “ecs00001” indicates that the UE must        make perform CS emergency call procedures if the UE selects the        CS domain to make the call. The UE must set the category in the        EMERGENCY SETUP message, and the UE only sets the bit        representing “police” (i.e. the first bit). The value of        “ps-emergency-type” portion is “sos.police”. The value        “sos.police” indicates that the UE must include a constructed        URN in the SIP INVITE if the UE selects the PS domain to make        the call or emergency session. The UE constructs a URN by        prepending “urn:service:” to the value, resulting in the        constructed URN “urn:service:sos.police”.

In embodiments with hexadecimal encoding, the above can be modified asfollows.

When a UE receives e.g.“sos.ambulance.cs.15.sos.en.cn.mcc345.pub.3gppnetwork.org” or“sos.police.ecs00001.17.sos.en.cn.mcc345.pub.3gppnetwork.org” and itdetects a dialed number matching:

-   -   15: the UE can derive from        “sos.ambulance.cs.15.sos.en.cn.mcc345.pub.3gppnetwork.org” that        numbed 15 matches the “emergency-number” portion (see Table        19.4.2.9A.x-1). Further, the value of the “cs-emergency” portion        is “CS”. The value “CS” indicates that the UE must perform CS        basic call procedures if the UE selects the CS domain to make        the call. The value of “ps-emergency-type” portion is        “sos.ambulance”. The value “sos.ambulance” indicates that the UE        must include a constructed URN in the SIP INVITE if the UE        selects the PS domain to make the call or emergency session. The        UE constructs a URN by prepending “urn:service:” to the value,        resulting in the constructed URN “urn:service:sos.ambulance”.    -   17: the UE can derive from        “sos.police.ecs00100.17.sos.en.cn.mcc345.pub.3gppnetwork.org”        that numbed 17 matches the “emergency-number” portion (see Table        19.4.2.9A.x-1). Further, the value of the “cs-emergency” portion        is “ecs01”. The value “ecs01” indicates that the UE must make        perform CS emergency call procedures if the UE selects the CS        domain to make the call. Hexadecimal value 01 represents value        00001 in 5 bits. The UE must set the 5-bit category in the        EMERGENCY SETUP message, and the UE only sets the bit        representing “police” (i.e. the first bit). The value of        “ps-emergency-type” portion is “sos.police”. The value        “sos.police” indicates that the UE must include a constructed        URN in the SIP INVITE if the UE selects the PS domain to make        the call or emergency session. The UE constructs a URN by        prepending “urn:service:” to the value, resulting in the        constructed URN “urn:service:sos.police”.

Some embodiments of the present disclosure may be described withreference to the following non limiting clauses.

1. A UE:

-   -   obtaining emergency information, the emergency information        including an emergency number and at least one of information to        initiate a call on a CS domain, information to initiate an        emergency session on a PS domain;    -   matching the emergency number with one or more first digits,        wherein the emergency number consists of one or more second        digits.

2. Item 1, wherein the call on the CS domain comprises at least one of abasic call or an emergency call.

3. Item 1, wherein information to initiate the emergency session on thePS domain comprises information to construct a URN.

3a. Item 3, wherein the URN includes a label set to “sos”.

4. Item 2, wherein information to initiate the emergency call on the CSdomain comprises information to construct a 5-bit service category.

5. Item 2, wherein information to initiate the emergency call on the CSdomain comprises a 5-bit service category.

6. Item 2, wherein information to initiate the basic call on the CSdomain comprises insufficient information to construct a 5-bit servicecategory.

7. Item 2, wherein information to initiate the basic call on the CSdomain comprises an indicator indicating the UE to initiate a basic callon the CS domain.

8. Item 2, wherein information to initiate the basic call on the CSdomain comprises an indication that emergency procedures are onlyapplicable on the PS domain.

9. Item 2, wherein information to initiate the basic call on the CSdomain comprises an indication that the one or more first digits areincluded in a CS SETUP message, if the emergency number matches the oneor more first digits.

10. Item 1, wherein the emergency number and at least one of informationare associated.

11. Item 3, wherein the URN is included in SIP INVITE message, if theemergency number matches the one or more first digits.

12. Item 3, wherein the URN includes a label equal to the emergencynumber, if a length field is set to zero.

13. Item 3, wherein the URN includes a label equal to the emergencynumber, if an indicator indicates the URN is a country specific URN.

13a. Item 3, wherein an indicator indicates the URN is a countryspecific URN.

13. Item 3, wherein an indicator indicates the URN is one of“urn:service:sos”, “urn:service:sos.police”,“urn:service:sos.ambulance”, “urn:service:sos.fire”,“urn:service:sos.marine”, “urn:service:sos.mountain”.

13a. Item 13, wherein the one of “urn:service:sos”,“urn:service:sos.police”, “urn:service:sos.ambulance”,“urn:service:sos.fire”, “urn:service:sos.marine”,“urn:service:sos.mountain” is derived from a 5-bit service category.

A. A network element, the network element:

-   -   providing emergency information, the emergency information        including an emergency number and at least one of information to        initiate a call on a CS domain, information to initiate an        emergency session on a PS domain.

AA. A system comprising the network element of item A and the UE of item1.

B. A network element in a first PLMN, the network element:

-   -   obtaining emergency information for a second PLMN, the emergency        information including an emergency number and at least one of        information to initiate a call on a CS domain, information to        initiate an emergency session on a PS domain;    -   the emergency information applicable when receiving a SIP INVITE        from a UE via the second PLMN.

B1. Item B, wherein the emergency information further indicates“emergency registration”.

B2. Item B, wherein the emergency information further indicates“anonymous-emergencycall”.

One example user equipment that may be used to implement the presentdisclosure is described below with regard to FIG. 4.

User equipment 400 may comprise a two-way wireless communication devicehaving voice or data communication capabilities or both. User equipment400 generally has the capability to communicate with other computersystems. Depending on the exact functionality provided, the userequipment may be referred to as a data messaging device, a two-waypager, a wireless e-mail device, a smartphone, a cellular telephone withdata messaging capabilities, a wireless Internet appliance, a wirelessdevice, a mobile device, an embedded cellular modem or a datacommunication device, as examples.

Where user equipment 400 is enabled for two-way communication, it mayincorporate a communication subsystem 411, including a receiver 412 anda transmitter 414, as well as associated components such as one or moreantenna elements 416 and 418, local oscillators (LOs) 413, and aprocessing module such as a digital signal processor (DSP) 420. As willbe apparent to those skilled in the field of communications, theparticular design of the communication subsystem 411 will be dependentupon the communication network in which the user equipment is intendedto operate.

Network access requirements will also vary depending upon the type ofnetwork 419. In some networks, network access is associated with asubscriber or user of the user equipment 400. A user equipment mayrequire an embedded or a removable user identity module (RUIM) or asubscriber identity module (SIM) card or a UMTS SIM (USIM) in order tooperate on a network. The USIM/SIM/RUIM interface 444 is normallysimilar to a card-slot into which a USIM/SIM/RUIM card can be insertedand ejected. The USIM/SIM/RUIM card can have memory and hold many keyconfigurations 451, and other information 453 such as identification,and subscriber related information. In other cases, rather than anetwork 419, user equipment 400 may communicate with a non-access node,such as a vehicle, roadside infrastructure, another user equipment, orother peer-to-peer communication.

When required network registration or activation procedures have beencompleted, user equipment 400 may send and receive communication signalsover the network 419. As illustrated in FIG. 4, network 419 can includemultiple base stations communicating with the mobile device.

Signals received by antenna 416 through communication network 419 areinput to receiver 412, which may perform such common receiver functionsas signal amplification, frequency down conversion, filtering, channelselection and the like. Analog to digital (A/D) conversion of a receivedsignal allows more complex communication functions such as demodulationand decoding to be performed in the DSP 410. In a similar manner,signals to be transmitted are processed, including modulation andencoding for example, by DSP 420 and input to transmitter 414 fordigital to analog (D/A) conversion, frequency up conversion, filtering,amplification and transmission over the communication network 419 viaantenna 418. DSP 420 not only processes communication signals, but alsoprovides for receiver and transmitter control. For example, the gainsapplied to communication signals in receiver 412 and transmitter 414 maybe adaptively controlled through automatic gain control algorithmsimplemented in DSP 420.

User equipment 400 generally includes a processor 438 which controls theoverall operation of the device. Communication functions, including dataand voice communications, are performed through communication subsystem411. Processor 438 also interacts with further device subsystems such asthe display 422, flash memory 424, random access memory (RAM) 426,auxiliary input/output (I/O) subsystems 428, serial port 430, one ormore keyboards or keypads 432, speaker 434, microphone 436, othercommunication subsystem 440 such as a short-range communicationssubsystem or DSRC subsystem, and any other device subsystems generallydesignated as 442. Serial port 430 could include a USB port, On-BoardDiagnostics (OBD) port or other port known to those in the art.

Some of the subsystems shown in FIG. 4 perform communication-relatedfunctions, whereas other subsystems may provide “resident” or on-devicefunctions. Notably, some subsystems, such as keyboard 432 and display422, for example, may be used for both communication-related functions,such as entering a text message for transmission over a communicationnetwork, and device-resident functions such as a calculator or tasklist.

Operating system software used by the processor 438 may be stored in apersistent store such as flash memory 424, which may instead be aread-only memory (ROM) or similar storage element (not shown). Thoseskilled in the art will appreciate that the operating system, specificdevice applications, or parts thereof, may be temporarily loaded into avolatile memory such as RAM 426. Received communication signals may alsobe stored in RAM 426.

As shown, flash memory 424 can be segregated into different areas forboth computer programs 458 and program data storage 450, 452, 454 and456. These different storage types indicate that each program canallocate a portion of flash memory 424 for their own data storagerequirements. Processor 438, in addition to its operating systemfunctions, may enable execution of software applications on the userequipment. A predetermined set of applications that control basicoperations, including potentially data and voice communicationapplications for example, will normally be installed on user equipment400 during manufacturing. Other applications could be installedsubsequently or dynamically.

Applications and software may be stored on any computer readable storagemedium. The computer readable storage medium may be a tangible or intransitory/non-transitory medium such as optical (e.g., CD, DVD, etc.),magnetic (e.g., tape) or other memory known in the art.

One software application may be a personal information manager (PIM)application having the ability to organize and manage data itemsrelating to the user of the user equipment such as, but not limited to,e-mail, messages, calendar events, voice mails, appointments, and taskitems. Further applications, including productivity applications, socialmedia applications, games, among others, may also be loaded onto theuser equipment 400 through the network 419, an auxiliary I/O subsystem428, serial port 430, short-range communications subsystem 440 or anyother suitable subsystem 442, and installed by a user in the RAM 426 ora non-volatile store (not shown) for execution by the processor 438.Such flexibility in application installation increases the functionalityof the device and may provide enhanced on-device functions,communication-related functions, or both.

In a data communication mode, a received signal such as a text messageor web page download will be processed by the communication subsystem411 and input to the processor 438, which may further process thereceived signal for output to the display 422, or alternatively to anauxiliary I/O device 428.

A user of user equipment 400 may also compose data items such asmessages for example, using the keyboard 432, which may be a completealphanumeric keyboard or telephone-type keypad, either physical orvirtual, among others, in conjunction with the display 422 and possiblyan auxiliary I/O device 428. Such composed items may then be transmittedover a communication network through the communication subsystem 411.

Where voice communications are provided, overall operation of userequipment 400 is similar, except that received signals may typically beoutput to a speaker 434 and signals for transmission may be generated bya microphone 436. Alternative voice or audio I/O subsystems, such as avoice message recording subsystem, may also be implemented on userequipment 400. Although voice or audio signal output is preferablyaccomplished primarily through the speaker 434, display 422 may also beused to provide an indication of the identity of a calling party, theduration of a voice call, or other voice call related information forexample.

Serial port 430 in FIG. 4 may be implemented in a user equipment forwhich synchronization with a user's desktop computer (not shown) may bedesirable, but is an optional device component. Such a port 430 mayenable a user to set preferences through an external device or softwareapplication and may extend the capabilities of user equipment 400 byproviding for information or software downloads to user equipment 400other than through a wireless communication network. As will beappreciated by those skilled in the art, serial port 430 can further beused to connect the user equipment to a computer to act as a modem orfor charging a battery on the user equipment.

Other communications subsystems 440, such as a short-rangecommunications subsystem, is a further component which may provide forcommunication between user equipment 400 and different systems ordevices, which need not necessarily be similar devices. For example, thesubsystem 440 may include an infrared device and associated circuits andcomponents or a Bluetooth™ or Bluetooth™ Low Energy communication moduleto provide for communication with similarly enabled systems and devices.Subsystem 440 may further include a WUR radio. Subsystem 440 may furtherinclude a DSRC radio. Subsystem 440 may further include non-cellularcommunications such as Wi-Fi or WiMAX, or near field communications, andin accordance with the embodiments above such radio may be capable ofbeing split in some circumstances.

The network elements described above can use any computing device orcombination of computing devices. One example computing device is shownwith regards to FIG. 5. Network element 510 includes a processor 520 anda communications subsystem 530, where the processor 520 andcommunications subsystem 530 cooperate to perform the methods of theembodiments described herein.

Processor 520 is configured to execute programmable logic, which may bestored, along with data, on network element 510, and shown in theexample of FIG. 5 as memory 540. Memory 540 can be any tangible,non-transitory computer readable storage medium, such as optical (e.g.,CD, DVD, etc.), magnetic (e.g., tape), flash drive, hard drive, or othermemory known in the art.

Alternatively, or in addition to memory 540, server 510 may access dataor programmable logic from an external storage medium, for examplethrough communications subsystem 530.

Communications subsystem 530 allows server 510 to communicate with otherdevices or network elements.

Communications between the various elements of server 510 may be throughan internal bus 560 in one embodiment. However, other forms ofcommunication are possible.

The embodiments described herein are examples of structures, systems ormethods having elements corresponding to elements of the techniques ofthis application. This written description may enable those skilled inthe art to make and use embodiments having alternative elements thatlikewise correspond to the elements of the techniques of thisapplication. The intended scope of the techniques of this applicationthus includes other structures, systems or methods that do not differfrom the techniques of this application as described herein, and furtherincludes other structures, systems or methods with insubstantialdifferences from the techniques of this application as described herein.

While operations are depicted in the drawings in a particular order,this should not be understood as requiring that such operations beperformed in the particular order shown or in sequential order, or thatall illustrated operations be performed, to achieve desirable results.In certain circumstances, multitasking and parallel processing may beemployed. Moreover, the separation of various system components in theimplementation descried above should not be understood as requiring suchseparation in all implementations, and it should be understood that thedescribed program components and systems can generally be integratedtogether in a signal software product or packaged into multiple softwareproducts.

Also, techniques, systems, subsystems, and methods described andillustrated in the various implementations as discrete or separate maybe combined or integrated with other systems, modules, techniques, ormethods. Other items shown or discussed as coupled or directly coupledor communicating with each other may be indirectly coupled orcommunicating through some interface, device, or intermediate component,whether electrically, mechanically, or otherwise. Other examples ofchanges, substitutions, and alterations are ascertainable by one skilledin the art and may be made.

While the above detailed description has shown, described, and pointedout the fundamental novel features of the disclosure as applied tovarious implementations, it will be understood that various omissions,substitutions, and changes in the form and details of the systemillustrated may be made by those skilled in the art.

When messages are sent to/from an electronic device, such operations maynot be immediate or from the server directly. They may be synchronouslyor asynchronously delivered, from a server or other computing systeminfrastructure supporting the devices/methods/systems described herein.The foregoing steps may include, in whole or in part,synchronous/asynchronous communications to/from thedevice/infrastructure. Moreover, communication from the electronicdevice may be to one or more endpoints on a network. These endpoints maybe serviced by a server, a distributed computing system, a streamprocessor, etc. Content Delivery Networks (CDNs) may also provide mayprovide communication to an electronic device. For example, rather thana typical server response, the server may also provision or indicate adata for content delivery network (CDN) to await download by theelectronic device at a later time, such as a subsequent activity ofelectronic device. Thus, data may be sent directly from the server, orother infrastructure, such as a distributed infrastructure, or a CDN, aspart of or separate from the system.

Typically, storage mediums can include any or some combination of thefollowing: a semiconductor memory device such as a dynamic or staticrandom access memory (a DRAM or SRAM), an erasable and programmableread-only memory (EPROM), an electrically erasable and programmableread-only memory (EEPROM) and flash memory; a magnetic disk such as afixed, floppy and removable disk; another magnetic medium includingtape; an optical medium such as a compact disk (CD) or a digital videodisk (DVD); or another type of storage device. Note that theinstructions discussed above can be provided on one computer-readable ormachine-readable storage medium, or alternatively, can be provided onmultiple computer-readable or machine-readable storage media distributedin a large system having possibly a plurality of nodes. Suchcomputer-readable or machine-readable storage medium or media is (are)considered to be part of an article (or article of manufacture). Anarticle or article of manufacture can refer to any manufactured singlecomponent or multiple components. The storage medium or media can belocated either in the machine running the machine-readable instructions,or located at a remote site from which machine-readable instructions canbe downloaded over a network for execution.

In the foregoing description, numerous details are set forth to providean understanding of the subject disclosed herein. However,implementations may be practiced without some of these details. Otherimplementations may include modifications and variations from thedetails discussed above.

1. A method by a User Equipment (UE) for using emergency information, comprising: transmitting a request message as part of a Network Access Stratum (NAS) procedure; receiving, in response to the request message, a response message comprising an emergency information including at least one emergency number; determining that a number matches the at least one emergency number; upon determining that the number matches the at least one emergency number, selecting a domain to perform a call setup procedure; when the selected domain is a Packet Switched (PS) domain, performing an emergency call setup procedure; and when the selected domain is a Circuit Switched (CS) domain, performing a CS fallback procedure without indicating CS fallback for emergency call depending on the emergency information.
 2. The method of claim 1, wherein the CS fallback procedure further comprises performing a basic call setup procedure.
 3. The method of claim 1, wherein the CS fallback procedure further comprises receiving a response message to a first SERVICE REQUEST message and subsequently sending a second service request message during the CS fallback procedure.
 4. The method of claim 1, wherein the emergency information includes a first information element (IE), the first IE comprising a list.
 5. The method of claim 4, wherein the first IE does not include a category for the at least one emergency number.
 6. The method of claim 4, wherein the emergency information includes a second IE comprising an Emergency Number List IE, wherein the first IE and the second IE are different.
 7. The method of claim 6, wherein the second IE comprises a category.
 8. The method of claim 1, wherein the NAS procedure comprises at least one of an attachment procedure, a tracking area update procedure, and a registration procedure.
 9. The method of claim 1, wherein the request message is at least one of a registration request to register, a request to update location information, or a request to update tracking area information.
 10. The method of claim 2, wherein the basic call setup procedure comprises sending a SETUP message with the emergency number.
 11. The method of claim 4, wherein the list comprises, for each of the at least one emergency number, information from which to derive an emergency Universal Resource Name (URN).
 12. The method of claim 11, wherein the emergency call setup procedure comprises sending an INVITE message with the emergency URN.
 13. The method of claim 1, wherein the NAS procedure comprises a procedure with a mobility management network element.
 14. A User Equipment (UE) comprising: a processor; and a communications subsystem; wherein the processor and the communications subsystem cooperate to: transmit a request message as part of a Network Access Stratum (NAS) procedure; receive, in response to the request message, a response message comprising a an emergency information including at least one emergency number; determine that a number matches the at least one emergency number; upon determining that the number matches the at least one emergency number, select a domain to perform a call setup procedure; when the selected domain is a Packet Switched (PS) domain, perform an emergency call setup procedure; and when the selected domain is a Circuit Switched (CS) domain, perform a CS fallback procedure without indicating CS fallback for emergency call depending on the emergency information.
 15. The UE of claim 14, wherein the CS fallback procedure further comprises performing a basic call setup procedure.
 16. The UE of claim 14, wherein the CS fallback procedure further comprises receiving a response message to a first SERVICE REQUEST message and subsequently sending a second service request message during the CS fallback procedure.
 17. The UE of claim 14, wherein the emergency information includes a first information element (IE), the first IE comprising a list.
 18. The UE of claim 17, wherein the first IE does not include a category for the at least one emergency number.
 19. The UE of claim 17, wherein the emergency information includes a second IE comprising an Emergency Number List IE, wherein the first IE and the second IE are different.
 20. The UE of claim 19, wherein the second IE comprises a category.
 21. The UE of claim 14, wherein the NAS procedure comprises at least one of an attachment procedure, a tracking area update procedure, and a registration procedure.
 22. The UE of claim 14, wherein the request message is at least one of a registration request to register, a request to update location information, or a request to update tracking area information.
 23. The UE of claim 15, wherein the basic call setup procedure comprises sending a SETUP message with the emergency number.
 24. The UE of claim 17, wherein the list comprises, for each of the at least one emergency number, information from which to derive an emergency Universal Resource Name (URN).
 25. The UE of claim 24, wherein the emergency call setup procedure comprises sending an INVITE message with the emergency URN.
 26. The UE of claim 14, wherein the NAS procedure comprises a procedure with a mobility management network element.
 27. A non-transitory computer readable medium having stored thereon executable code for execution by a processor of a User Equipment (UE), the executable code comprising instructions for: transmitting a request message as part of a Network Access Stratum (NAS) procedure; receiving, in response to the request message, a response message comprising an emergency information including at least one emergency number; determining that a number matches the at least one emergency number; upon determining that the number matches the at least one emergency number, selecting a domain to perform a call setup procedure; when the selected domain is a Packet Switched (PS) domain, performing an emergency call setup procedure; and when the selected domain is a Circuit Switched (CS) domain, performing a CS fallback procedure without indicating CS fallback for emergency call depending on the emergency information. 